{"id":{"repo_id":"washington","oai_identifier":"oai:digital.lib.washington.edu:1773/26277"},"canonical_url":"https://search.dev.ndltd.org/etd/washington/oai:digital.lib.washington.edu:1773/26277","repository":{"repo_id":"washington","name":"University of Washington","base_url":"https://digital.lib.washington.edu/server/oai/request"},"display":{"title":"Utilizing Changes in Repeating Earthquakes to Monitor Evolving Processes and Structure Before and During Volcanic Eruptions","abstract":"Repeating earthquakes are two or more earthquakes that share the same source location and source mechanism, which results in the earthquakes having highly similar waveforms when recorded at a seismic instrument. Repeating earthquakes have been observed in a wide variety of environments: from fault systems (such as the San Andreas and Cascadia subduction zone), to hydrothermal areas and volcanoes. Volcano seismologists are particularly concerned with repeating earthquakes, as they have been observed at volcanoes along the entire range of eruptive style and are often a prominent feature of eruption seismicity. The behavior of repeating earthquakes sometimes changes with time, which possibly reflects subtle changes in the mechanism creating the earthquakes. In Chapter 1, we document an example of repeating earthquakes during the 2009 eruption of Redoubt volcano that became increasingly frequent with time, until they blended into harmonic tremor prior to several explosions. We interpreted the source of the earthquakes as stick-slip on a fault near the conduit that slipped increasingly often as the explosion neared in response to the build-up of pressure in the system. The waveforms of repeating earthquakes may also change, even if the behavior does not. We can quantify changes in waveform using the technique of coda wave interferometry to differentiate between changes in source and medium. In Chapters 2 and 3, we document subtle changes in the coda of repeating earthquakes related to small changes in the near-surface velocity structure at Mount St. Helens before and during its eruption in 2004. Velocity changes have been observed prior to several volcanic eruptions, are thought to occur in response to volumetric strain and the opening or closing of cracks in the subsurface. We compared continuous records of velocity change against other geophysical data, and found that velocities at Mount St. Helens change in response to snow loading, fluid saturation, shaking from large distant earthquakes, shallow pressurization, and possibly lava extrusion. Velocity changes at Mount St. Helens are a complex mix of many different effects, and other complementary data are required to interpret the signal.","abstract_html":"Repeating earthquakes are two or more earthquakes that share the same source location and source mechanism, which results in the earthquakes having highly similar waveforms when recorded at a seismic instrument. Repeating earthquakes have been observed in a wide variety of environments: from fault systems (such as the San Andreas and Cascadia subduction zone), to hydrothermal areas and volcanoes. Volcano seismologists are particularly concerned with repeating earthquakes, as they have been observed at volcanoes along the entire range of eruptive style and are often a prominent feature of eruption seismicity. The behavior of repeating earthquakes sometimes changes with time, which possibly reflects subtle changes in the mechanism creating the earthquakes. In Chapter 1, we document an example of repeating earthquakes during the 2009 eruption of Redoubt volcano that became increasingly frequent with time, until they blended into harmonic tremor prior to several explosions. We interpreted the source of the earthquakes as stick-slip on a fault near the conduit that slipped increasingly often as the explosion neared in response to the build-up of pressure in the system. The waveforms of repeating earthquakes may also change, even if the behavior does not. We can quantify changes in waveform using the technique of coda wave interferometry to differentiate between changes in source and medium. In Chapters 2 and 3, we document subtle changes in the coda of repeating earthquakes related to small changes in the near-surface velocity structure at Mount St. Helens before and during its eruption in 2004. Velocity changes have been observed prior to several volcanic eruptions, are thought to occur in response to volumetric strain and the opening or closing of cracks in the subsurface. We compared continuous records of velocity change against other geophysical data, and found that velocities at Mount St. Helens change in response to snow loading, fluid saturation, shaking from large distant earthquakes, shallow pressurization, and possibly lava extrusion. Velocity changes at Mount St. Helens are a complex mix of many different effects, and other complementary data are required to interpret the signal.","abstract_has_math":false,"creators":["Hotovec-Ellis, Alicia Jean"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Vidale, John E"],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-10-13","date_published":"2014-10-13","updated_at":"2026-07-24T05:58:14Z","subjects":["coda-wave interferometry; Mount St. Helens; Redoubt Volcano; repeating earthquakes; volcanic tremor; volcano seismology"],"languages":["en_US"],"rights":["Copyright is held by the individual authors."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1773/26277","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Vidale, John E"]},{"key":"dc:creator","label":"Author","values":["Hotovec-Ellis, Alicia Jean"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-10-13T19:56:46Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-10-13T19:56:46Z"]},{"key":"dc:date.issued","label":"Date","values":["2014-10-13"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["coda-wave interferometry; Mount St. Helens; Redoubt Volcano; repeating earthquakes; volcanic tremor; volcano seismology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright is held by the individual authors."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["HotovecEllis_washington_0250E_13100.pdf"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1773/26277"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (Ph.D.)--University of Washington, 2014"]},{"key":"dc:description.abstract","label":"Abstract","values":["Repeating earthquakes are two or more earthquakes that share the same source location and source mechanism, which results in the earthquakes having highly similar waveforms when recorded at a seismic instrument. Repeating earthquakes have been observed in a wide variety of environments: from fault systems (such as the San Andreas and Cascadia subduction zone), to hydrothermal areas and volcanoes. Volcano seismologists are particularly concerned with repeating earthquakes, as they have been observed at volcanoes along the entire range of eruptive style and are often a prominent feature of eruption seismicity. The behavior of repeating earthquakes sometimes changes with time, which possibly reflects subtle changes in the mechanism creating the earthquakes. In Chapter 1, we document an example of repeating earthquakes during the 2009 eruption of Redoubt volcano that became increasingly frequent with time, until they blended into harmonic tremor prior to several explosions. We interpreted the source of the earthquakes as stick-slip on a fault near the conduit that slipped increasingly often as the explosion neared in response to the build-up of pressure in the system. The waveforms of repeating earthquakes may also change, even if the behavior does not. We can quantify changes in waveform using the technique of coda wave interferometry to differentiate between changes in source and medium. In Chapters 2 and 3, we document subtle changes in the coda of repeating earthquakes related to small changes in the near-surface velocity structure at Mount St. Helens before and during its eruption in 2004. Velocity changes have been observed prior to several volcanic eruptions, are thought to occur in response to volumetric strain and the opening or closing of cracks in the subsurface. We compared continuous records of velocity change against other geophysical data, and found that velocities at Mount St. Helens change in response to snow loading, fluid saturation, shaking from large distant earthquakes, shallow pressurization, and possibly lava extrusion. Velocity changes at Mount St. Helens are a complex mix of many different effects, and other complementary data are required to interpret the signal."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Utilizing Changes in Repeating Earthquakes to Monitor Evolving Processes and Structure Before and During Volcanic Eruptions"]}]}],"canonical_facts":{"dc:contributor.advisor":["Vidale, John E"],"dc:creator":["Hotovec-Ellis, Alicia Jean"],"dc:date.accessioned":["2014-10-13T19:56:46Z"],"dc:date.available":["2014-10-13T19:56:46Z"],"dc:date.issued":["2014-10-13"],"dc:description":["Thesis (Ph.D.)--University of Washington, 2014"],"dc:description.abstract":["Repeating earthquakes are two or more earthquakes that share the same source location and source mechanism, which results in the earthquakes having highly similar waveforms when recorded at a seismic instrument. Repeating earthquakes have been observed in a wide variety of environments: from fault systems (such as the San Andreas and Cascadia subduction zone), to hydrothermal areas and volcanoes. Volcano seismologists are particularly concerned with repeating earthquakes, as they have been observed at volcanoes along the entire range of eruptive style and are often a prominent feature of eruption seismicity. The behavior of repeating earthquakes sometimes changes with time, which possibly reflects subtle changes in the mechanism creating the earthquakes. In Chapter 1, we document an example of repeating earthquakes during the 2009 eruption of Redoubt volcano that became increasingly frequent with time, until they blended into harmonic tremor prior to several explosions. We interpreted the source of the earthquakes as stick-slip on a fault near the conduit that slipped increasingly often as the explosion neared in response to the build-up of pressure in the system. The waveforms of repeating earthquakes may also change, even if the behavior does not. We can quantify changes in waveform using the technique of coda wave interferometry to differentiate between changes in source and medium. In Chapters 2 and 3, we document subtle changes in the coda of repeating earthquakes related to small changes in the near-surface velocity structure at Mount St. Helens before and during its eruption in 2004. Velocity changes have been observed prior to several volcanic eruptions, are thought to occur in response to volumetric strain and the opening or closing of cracks in the subsurface. We compared continuous records of velocity change against other geophysical data, and found that velocities at Mount St. Helens change in response to snow loading, fluid saturation, shaking from large distant earthquakes, shallow pressurization, and possibly lava extrusion. Velocity changes at Mount St. Helens are a complex mix of many different effects, and other complementary data are required to interpret the signal."],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["HotovecEllis_washington_0250E_13100.pdf"],"dc:identifier.uri":["http://hdl.handle.net/1773/26277"],"dc:language.iso":["en_US"],"dc:rights":["Copyright is held by the individual authors."],"dc:subject":["coda-wave interferometry; Mount St. Helens; Redoubt Volcano; repeating earthquakes; volcanic tremor; volcano seismology"],"dc:title":["Utilizing Changes in Repeating Earthquakes to Monitor Evolving Processes and Structure Before and During Volcanic Eruptions"],"dc:type":["Thesis"]},"updated_at":"2026-07-24T05:58:14Z"}